[Cryptography] handling the "Double Spend Problem" pure cryptography and math (no consensus)

[Peter Fairbrother]

On 13/04/2025 14:53, Cryptskii via cryptography wrote:
[...]

> https://eprint.iacr.org/2025/592

Very hard to read, and full of word-salad/AI alarm signs. It also put a 
lot of stuff that is fairly normal in new fancy words and claimed it as 
new :(.

Anywhoo, I skimmed to page 54 (of 116) and couldn't see how it solved 
the double-spend problem.

Could we have that part on a postcard please?

Hint: Alice has some state on her mobile phone device which allows her 
to convince Bob etc's device that she can/is paying him offline without 
reference to any other devices anywhere. Why can't she clone the state 
and repeat with Charles or Dan or Ellie or Fred's devices...? Note, no 
reference to any other device is allowed until much later.

I personally think it is impossible to prevent this double-spend attack, 
bicbw. Data is not like things - If I give you a thing I no longer have 
it, if I give you some data I can still have it too.


Peter Fairbrother